"Similar to most of my fellow MTV cast mates, I am in utter shock at the allegations made against Adam DiVello," she tells UsMagazine.com in a statement. "Not only are they completely absurd, but they are 100 percent without merit. Adam is a true professional and a wonderful person to work for."

Hilton quoted a source as saying: "Adam can get away with that with the Audrinas and Kristins of reality TV but not with Heidi! He is a pervert and a creep. The other girls don't feel they can't defend themselves because they are afraid they will lose their job if they talk about the man's workplace behavior. Heidi will not tolerate sexual assault in the workplace!"

Montag and her husband Spencer Pratt "are very close to bringing legal action against the show," an insider told Hilton.

An MTV spokesperson tells Us: "We have looked into this matter and the allegations made against Adam DiVello are completely false and without merit. Adam not only created The Hills and The City, launching the careers of several cast members, but has worked diligently to maintain a respectful and appropriate production environment."

It's not the first on-set drama for Montag and Pratt, 26.

In March, Us reported that Pratt was asked to leave The Hills for six weeks after he "flipped out" on-set after a female producer made a request to which he objected. "He got so crazy that he screamed at [her], 'I should kill you for even asking me to do that!'" the source told Us.

"Very rattled" by Pratt's outburst, the producer filed a complaint with the show's top producers -- who then threatened to kick Pratt off the show.

Pratt's team went back with a compromise: "The show agreed that Spencer would leave The Hills for six weeks to do anger management training once a week at home," said a source. "If he completes it, he can return to the show."